非平稳性条件下设计洪水地区组成分析

针对非平稳性条件下不同区域洪水间组合设计值计算难题，采用Copula函数构建了可综合考虑不同区域洪水边缘分布非平稳性和洪水间相依结构非平稳性的变参数Copula模型，分析了不同区域洪水间联合分布规律随时间的演变特征。基于等可靠度法和条件期望组合法，提出了变化环境下设计洪水地区组成分析方法，实现了非平稳性条件下不同区域洪水组合设计值的计算。以寸滩站和宜昌站年最大15 d洪量系列为例，分析了两站洪量及其区间洪量的变化特征。结果表明，寸滩站和宜昌站的洪量系列均具有减少趋势，两站洪量的联合分布随时间变化，指定重现期对应的宜昌站、寸滩站及寸滩—宜昌区间洪水设计值随使用年限的增加而减小。

Analysis of regional composition of design flood under non-stationary conditions

To address the problem of calculating the combined design value of different regional flood under non-stationary conditions, this paper firstly constructs a varying-parameter Copula model based on the Copula function, which can consider the non-stationarity of the marginal distribution of different flood variables and the non-stationarity of their dependence structure. The non-stationary evolution characteristics of the joint distribution of floods in different regions over time are analyzed. Based on the equal reliability method and the conditional expectation combination method, a method for analyzing the regional composition of non-stationary design floods under changing environments is proposed, which can be used to calculate the design value combinations of different regional floods corresponding to a specified return period under non-stationary conditions. Based on the annual maximum 15-day flood volume (AM15FV) series at Cuntan and Yichang stations, the proposed method is used to analyze the change on design flood combinations among the Cuntan, Yichang and Cuntan-Yichang section. The results show that the AM15FV series at Cuntan and Yichang stations exhibits a decreasing trend, and their joint distribution of floods at Cuntan and Yichang stations varies with time. The design values of floods at Yichang station, Cuntan station and Cuntan-Yichang section corresponding to the specified return period tend to decrease with increasing design lifetime.